Drier control system



Jan. 9, 1945. R. E. OLSON I DRIER CONTROL SYSTEM Filed Sept. 10 1942 w LI i I.

INVENTOR R5 OLSO/V BY ATTOR Y Patented Jan. 9, 19 45 UNITED .STATES"PATENT OFFICE 2,366,801 3 n DRIER CONTROL SYSTEM Raymond E. Olson,Pittsl'ord, N. Y., asslgnor to Taylor Instrument Companies, Rochester,N. Y., a corporation of New York Application September 10, 1942, SerialNo. 457,887 I (Cl. 3441) l 1 trolled by a diaphragm motor valve 8connected 3 Claims.

This invention relates to driers and particularly to driers of the typecomprising one or more drums, internally heated'by steam'or othersimilar heating fluid. The'drums of such driers are preferablypneumatically flushed of steam condensate and are also providedwith-vacuum relief means whereby atmospheric pressure, is establishedwithin the drums to prevent them from collapsing as would otherwiseoccur when the drums cooled oii' atthetimepf shut-down.

therein, which valve is adaptedto be closed by a pressure fluid, such ascompressedair applied to its diaphragm motor. The application ofcompressed air to thisdiaphragm motor is governed by a suitabletemperature controller including a thermosensitive bulb B, similar tothat shown in Fig. 1 of-Foote Patent No. 2,088,055, granted July 27,1937. The controller 0, as herein uti-' With th drums thus filled withair, it has been difficult in the starting of prior driers, to bringthem up to predetermined temperature quickly since the air trapped inthe drums tended to oppose the introduction of steam therein.

, In accordance with the present invention, means are provided forautomatically venting the air from the drums until such time as theyreach 7 a predetermined temperature after which the automatic ventingmeans ceases to operate until the drums are again below the mentionedtemperature.

Another feature of the invention relates to a drier having steam heateddrums from which steam condensate is pneumatically flushed and means iorventing the air from said drums under the-control densate.

Various other features of the invention will appear from the detaileddescription and claims when taken with the drawing in which:

vFig. 1 is a diagrammatic showing of a drum of the temperature'of saidcon-- i type drier incorporating the present invention;

a a Fig. 2 is a diagrammatic showing of the automatic vacuumrelief valveand of the piping arrangement for introducing steam into each drum,

as well as for pneumatically removing steam condensate ther rom.

The present invention is applied to a drier comprising -a plurality ofdriven drums 5a, 5b

and 5c, provided with s'uitable trunnions 6 on which they are rotatablein parallel relation so that astrip S to be dried, passes in a-zigzagpath thereabout (Fig. 1). While three drums only are illustrated, itwill be understood that the invention is not limited to any given numberthereof but is applicable to one drum or any number of drums, asoccasion demands.

The drums are preferably internally heated by steam' supplied through aheader 1 having branches In respectively communicating through atrunnion. 8 cl each of the several drums in,

lized, operates in response to temperature changes in the steamcondensate, sensed by the bulb B, to govern the application ofcompressed air from the supply pipe 22 through conduit 9 to the motor ofvalve 8 and to branch conduit 9a, which through its individual trap l2wi a common condensate pipe J3. In order to sense the'temperature of thecondensate, the bulb B is mounted in one of the exhaust pipes Hexternally ofits related drum. The interior of each drum duringoperation, is also supplied with compressed air or like pressure mediumby means of the supply pipe l4 and its branches 14a which respectivelypass through a trunnion of each of the several drums. This compressedair serves to flush the condensate from thedrums into the exhaust pipesII and thence into condensate pipe l3 thru the steam traps 'l 2. It willbe noted that each branch air pipe Ma has a check valve l5 therein toprevent steam from passing into the main air supply pipe it. Eachexhaust pipe II also communicates through a check valve H with a commonair vent pipe l8 which opens directly into the condensate discharge pipel3. The 'checlkyalves ll 'prevent the interflow of the pressure me diumsthrough the vent pipe l8 between the several'drums. The flow through airvent pipe 18 is governed by a diaphragm motor valve I19 which is closedby the application of compressed air to its motor. to this motor isgoverned by the relay valve III which is opened by the application ofcompressed air thereto through the conduit 9a. It will be noted thatconduit communicates with conduit 9 so that relay valve II is openedwhen the The application of compressed air H ply is turned off such aswhen the drier is shut down, the drums cool so that thecontained steamand air contract developing subatmospheric pressures therein. In orderto restore the interior of the drums to atmospheric pressure and therebyprevent the collapse thereof, an automatic vacuum release valve 20 isprovided in each drum to open to the atmosphere in response tosubatmospheric pressure therein.

Let it be assumed that it is desired to start the drier when the drumsa, 5b and 50 thereof are cold and when they contain air at atmosphericpressure. At this time the motor valve 8 in the steam header 1 will beopen and the motor valve IS in the air vent pipe 18 will likewise beOpen. It is further assumed that a supply of steam under pressure isavailable at the header I and that a; supply of compressed air isavailable in the air supply pipe l4. Under these conditions, steam willbe introduced through the header 1 and its branches Ia into therespective drums andthe air present within the drums is forced outthrough the air vent pipe I8. Since the drums are cold and since theywill continue to give off heat during the drying operation, the steamwill condense in the drums from which the condensate is flushed throughthe respective syphon exhaust pipes II by compressed air applied throughbranch pipes Ila. When the temperature of the condensate at the bulb Bof the controller C reaches a predetermined temperature, the controllerC will operate to apply compressed air through the supply pipe '22 tothe diaphragm. motor of the valve 8 and also to the operating chamber ofthe relay valve i0. Motor valve '8 in response to this pressure in itsmotor, as applied by controller C, will throttle the valve IS in the airvent pipe. Valve l9 thus op-- erates to close the air vent pipe.Thereafter, the operation of the drier is in accordance with the usualprocedure wherein the condensate is discharged through the syphonexhaust pipes ll steam applied to the several drums to maintain and theseveral individual mon condensate pipe".

WhatIclaimis: 1. The method of starting the operation of a drier,comprising a. plurality of hollow drums which. are arranged to be heatedby a heating fluid introduced therein and which are provided with vacuumrelease mechanism whereby the space within said drums fills with airwhen the drier is shut down, which method comprises introducing steaminto said drums while venting air therefrom, removing the condensatefrom said traps I! to the comdrums, sensing the temperature 0! thecondeni sate in one of said drums, terminating the vent ing of saiddrums responsive to the attainment of a predetermined temperature ofsaid condensate, and throttling the heating fluid introduced into saiddrums in response to the variation of a given value of the sensedtemperature 01 said condensate to maintain said drums at a desiredtemperature which is greater than saidpredetermined temperature. 1

2. In a drier having a hollow drum, a pipe for supplying a heatingmedium to the interior of said drum, a valve connected in said pipe forgoverning the flow of the heating medium therethrough, means forrelieving subatmospheric conditions within said drum, a conduit having-anormally-open valve connected therein to vent said drum, means fordischarging condensate from said drum, and a controller operative sub--stantially in accordance with a predetermined temperature within saiddrum for throttling said first mentioned valveandfor closing saidlastmentione'd valve throughout the throttlinge operation.

3. In a drier having a hollow drum, a pipe for j supplyingsteam to theinterior of said drum, a

diaphragm motor valve connected in said pipe for governing the flow ofsteam therethrough, means for relieving 's'ubatmospheric conditionswithin said drum, means for flushing condensate from saiddrum, a conduithaving a normally. open valve connected therein to vent said drum,

means for discharging condensate-from said drum and a controllerresponsive to. a predetermined temperature or said condensate forthrottling said first-mentioned valve and ,for closing s aid'last-mentioned valve.

' RAYMOND n; OLSON.

